Single Ended Tokin SIT THF-51S Common Drain Mu Follower Amplifier, 45W?

[Citation19]

Well... understanding that describing amplifier sound signatures is subjective.My first impressions would be.....

System...
Speakers are Voight Pipes (Tang Band) with midbass horns and subs Crossed at 80hz. Forwatt SRPP Preamp (Bruce Heran) / 6-24 crossover / BOZ pre used after the crossover as a FE (BA3 and 2022 Burning Amp FE on the bench now.)

So...first impressions
Lots of clarity / high frequencies are very articulate yet not bright / 3d imagery is more present than I have had previously / midrange tonal character is still warm but not really bloomy / can not comment fully on bass as I am using this above 80hz but mid bass performance seems fine./ If you have a poor recording this amp will not just let you know, it will stand up , point, and mock the flaws.

In comparison...
I love the Aleph J however in comparison to this Sit Muff set up, I would say the Aleph J is a little .....syrupy ?.(Sometimes we like a little syrup....hmm).
Saying the Aleph is warmer is not really correct to my ears....the Muff is also warm but without rounding off and losing some detail.
I get the feeling the Aleph J kind of suggests what it thinks the speaker should do while this amp DEMANDS the speaker do its bidding and it better be damn quick about it.(just a gut feeling here possibly some smarter folks could comment on damping factor differences and such )

Very much pleased to have built both!

Would again like to thank Nelson and Ben for the expertise that was just handed out for free here.The value of these gifts is not lost on me !

 

[mordikai]

wow, you're much better at describing what you hear than I am.

 

[Vunce]

Congratulations Citation19 on your successful build!
Your description about suggestion vs demand makes perfect sense to me. Well done

 

[grataku]

Latest addition

4 or 5 sessions in and everything is holding up nicely. It's a different experience than listening with my Aleph J.

different how?

 

[Ben Mah]

Congratulations Citation19 on a successful build. This is the first time that I have designed a PCB and shared it so I am happy that it went well. Do you have both channels built or are you listening to one channel?

Your description of the sound is similar to my experience. SIT followers have a clarity that is very natural but not bright. I am enjoying the sound right now.

 

[Citation19]

Both channels are built....I eagerly await to see what the BA-3FE (or BA2022FE) will bring to the party. The BOZ is doing the job but likely isn't ideal.

Ben's guidance towards the chassis/heatsink build was spot on. After 3 to 4 hrs (@2.5 amps) the heatsinks just behind the devices reads around 52 deg. C with an IF thermometer. You can place your hands on the outer fins of the sinks indefinitely. Internal temperature at the PS capacitors (with fan overhead) levels off at 40 deg C and appears to stay there. The pcb mounted capacitors near the resistor array read 42-45 Deg C.

I may be drilling holes in the chassis base (as suggested here)as the summer temps approach.

Very pleased.

 

[grataku]

Impressions on the sound?

 

[Citation19]

Grataku...I did a sound quality impression & review 6 comments back. I can repost it but feel I've occupied enough of this chat and look forward to some of the other builds. Let me know.

 

[grataku]

woops, i didnt see that. I'll check it.

 

[derekr]

Congrats on the build, Citation19. You might let that lizard know Very Few Ever Tolerate SITting on hot heatsinks….cremation looms!

 

[ggetzoff]

Any boards out there? If not, I will order some (providing Ben sends me Gerbers) 😁

 

[BRN]

I may have so boards if you still need. Send me a PM

 

[rtylr]

Thanks for the comparison @Citation19, much appreciated!

 

[Ben Mah]

I finished building Nelson's DIY FE 2022 and it sounds great. It has very low distortion so I was able to do some new FFT runs of the THf-51S Mu follower follower amp. With the low distortion signal from the DIY FE 2022 feeding the amplifier, a more accurate reading of the amplifier's distortion is possible compared to the higher distortion 2SK79 preamp that I was using previously. The DIY FE 2022 has lower gain though so I was only able to test the amplifier to 35W into 8R.

The FFT results for the DIY 2022FE are here: My DIY FE 2022 FFTs

The new FFTs for the right channel are below. The distortion numbers are significantly lower as expected.

 

[Ben Mah]

And here is the left channel:

 

[ggetzoff]

Ben, as usual great work. Any subjective comments on its performance would br great.

 

[Ben Mah]

Greg, The change is similar to the change from common source to common drain, but the step is smaller. It is similar in that there is increased clarity and detail, but not a big increase, but yet very noticeable. The result is a bit more realism. I think the reason for the small perceived change that I hear is that since my speakers are 103dB sensitive, the system (preamp and amplifier) only needs to output 1 Watt or less most of the time. So with either preamp operating at its lower output voltage, the distortion level is not very high, and for both the distortion is second harmonic dominant, with some third harmonic, and other higher harmonics much lower. So similar sound, but the DIY FE 2022 has the advantage, but I could still live with the 2SK79 in my system. Perhaps if I need to push my 2SK79 preamp to higher output levels, that would change. But my sensitive speakers do not need many Watts so I do not need many Volts from my preamps.

Over the years my preferences have slowly changed. I used to like single ended triodes. Then I went to single ended SITs with voltage gain, and now single ended SITs with no voltage gain. And preamp from 26 triode to single ended 2SK82 (Luminaria) to single ended 2SK79 to DIY FE 2022. In all cases distortion levels dropped each time.

And even though at each stage along the way, I enjoyed the sound and thought it was great, each change made me realize that what was "great" could be bettered. And the decrease in the good second and third harmonics did not result in shrill sound - just keep all the other higher harmonics at a much lower level and all is good.

 

[sp33ls]

Sounds like you'll end up in the ultra-low distortion camp if this trend continues, Ben.

 

[Ben Mah]

I think that this is as low as I need to go.

No Class D for me!

 

[Zen Mod]